Fig. 3.

CircStrn3 was involved in the regulation of chondrocyte extracellular matrix production by mechanical stress. a) Complementation between circStrn3 and ‘seed sequence’ of microRNA (miR)-9-5p. b) The results of quantitative real-time polymerase chain reaction (qRT-PCR) showed that expression of miR-9-5p was increased in cartilage and chondrocytes from osteoarthritis (OA) patients (n = 4, **p < 0.01). c) Fluorescence in situ hybridization (FISH) staining results showed that miR-9-5p was upregulated in human chondrocytes (n = 4, scale bar: 10 μm). d) qRT-PCR tested the expression of miR-9-5p in chondrocytes exposed to mechanical loading or control condition (n = 4, **p < 0.001). e) to f) qRT-PCR tested the expressions of e) circStrn3 and f) miR-9-5p in chondrocytes transfected with circStrn3 or circNC (n = 4, **p < 0.01). g) The results showed a significant decrease in firefly luciferase activity when wild type (WT) was cotransfected with miR-9-5p mimics, thus no significant change was observed in luciferase activity after co-transfection with mutation type (Mut) and miR-9-5p mimic (n = 4, **p < 0.01). h) FISH staining results showed that circStrn3 colocalized with miR-9-5p in the cytoplasm. (n = 6, scale bar: 10 μm). Independent-samples t-test was used to compare data between two groups, and one-way analysis of variance was used for comparison between multiple groups. DAPI, 4′,6-diamidino-2-phenylindole; NC, negative control.